Bresenham's Line Drawing Algorithm
#include< graphics.h >
void drawline(int x0, int y0, int x1, int y1)
{
int dx, dy, p, x, y;
dx=x1-x0;
dy=y1-y0;
x=x0;
y=y0;
p=2*dy-dx;
while(x
if(p>=0)
{
putpixel(x,y,7);
y=y+1;
p=p+2*dy-2*dx;
}
else
{
putpixel(x,y,7);
p=p+2*dy;}
x=x+1;
}
}
int main()
{
int gdriver=DETECT, gmode, error, x0, y0, x1, y1;
initgraph(&gdriver, &gmode, "c:\\turboc3\\bgi");
printf("Enter co-ordinates of first point: ");
scanf("%d%d", &x0, &y0);
printf("Enter co-ordinates of second point: ");
scanf("%d%d", &x1, &y1);
drawline(x0, y0, x1, y1);
return 0;
}
Circle Using Bradenham's Circle Algorithm
To implemet midpoint circle generation algorithm or bresenham's circle algorithm for drawing a circle of given center (x,y) and radius r
#include < dos.h >
#include < graphics.h >
void drawCircle(int xc, int yc, int x, int y)
{
putpixel(xc+x, yc+y, RED);
putpixel(xc-x, yc+y, RED);
putpixel(xc+x, yc-y, RED);
putpixel(xc-x, yc-y, RED);
putpixel(xc+y, yc+x, RED);
putpixel(xc-y, yc+x, RED);
putpixel(xc+y, yc-x, RED);
putpixel(xc-y, yc-x, RED);
}
void circleBres(int xc, int yc, int r)
{
int x = 0, y = r;
int d = 3 - 2 * r;
drawCircle(xc, yc, x, y);
while (y >= x)
{
x++;
if (d > 0)
{
y--;
d = d + 4 * (x - y) + 10;
}
else
d = d + 4 * x + 6;
drawCircle(xc, yc, x, y);
delay(50);
}
}
int main()
{
int xc = 50, yc = 50, r = 30;
int gd = DETECT, gm;
initgraph(&gd, &gm, ""); // initialize graph
circleBres(xc, yc, r);
return 0;
}
Ellipse Generation Algorithm
#include < stdlib.h >
#include < math.h >
#include < stdio.h >
#include < conio.h >
#include < iostream.h >
class bresen
{
float x,y,a, b,r,p,h,k,p1,p2;
public:
void get ();
void cal ();
};
void main ()
{
bresen b;
b.get ();
b.cal ();
getch ();
}
void bresen :: get ()
{
cout<<"\n ENTER CENTER OF ELLIPSE";
cout<<"\n ENTER (h, k) ";
cin>>h>>k;
cout<<"\n ENTER LENGTH OF MAJOR AND MINOR AXIS";
cin>>a>>b;
}
void bresen ::cal ()
{
/* request auto detection */
int gdriver = DETECT,gmode, errorcode;
int midx, midy, i;
/* initialize graphics and local variables */
initgraph (&gdriver, &gmode, " ");
/* read result of initialization */
errorcode = graphresult ();
if (errorcode ! = grOK) /*an error occurred */
{
printf("Graphics error: %s \n", grapherrormsg (errorcode);
printf ("Press any key to halt:");
getch ();
exit (1); /* terminate with an error code */
}
x=0;
y=b;
// REGION 1
p1 =(b * b)-(a * a * b) + (a * a)/4);
{
putpixel (x+h, y+k, RED);
putpixel (-x+h, -y+k, RED);
putpixel (x+h, -y+k, RED);
putpixel (-x+h, y+k, RED);
if (p1 < 0)
p1 += ((2 *b * b) *(x+1))-((2 * a * a)*(y-1)) + (b * b);
else
{
p1+= ((2 *b * b) *(x+1))-((2 * a * a)*(y-1))-(b * b);
y--;
}
x++;
}
//REGION 2
p2 =((b * b)* (x + 0.5))+((a * a)*(y-1) * (y-1))-(a * a *b * b);
while (y>=0)
{
If (p2>0)
p2=p2-((2 * a * a)* (y-1))+(a *a);
else
{
p2=p2-((2 * a * a)* (y-1))+((2 * b * b)*(x+1))+(a * a);
x++;
}
y--;
putpixel (x+h, y+k, RED);
putpixel (-x+h, -y+k, RED);
putpixel (x+h, -y+k, RED);
putpixel (-x+h, y+k, RED);
}
getch();
}
Boundary Fill Algorithm
#include < stdio. h >
#include < dos.h >
// Function for 4 connected Pixels
void boundaryFill4(int x, int y, int fill_color,int boundary_color)
{
if(getpixel(x, y) != boundary_color &&
getpixel(x, y) != fill_color)
{ putpixel(x, y, fill_color);
boundaryFill4(x + 1, y, fill_color, boundary_color);
boundaryFill4(x, y + 1, fill_color, boundary_color);
boundaryFill4(x - 1, y, fill_color, boundary_color);
boundaryFill4(x, y - 1, fill_color, boundary_color);
}
}
//driver code
int main()
{
int gd = DETECT, gm;
initgraph(&gd, &gm, " ");
int x = 250, y = 200, radius = 50;
// circle function
circle(x, y, radius);
// Function calling
boundaryFill4(x, y, 6, 15);
delay(10000);
getch();
closegraph();
return 0;
}
Flood Fill Algorithm
#include < stdio.h >
void flood(int x, int y, int new_col, int old_col)
{
if (getpixel(x, y) == old_col) {
putpixel(x, y, new_col);
flood(x + 1, y, new_col, old_col);
flood(x - 1, y, new_col, old_col);
flood(x, y + 1, new_col, old_col);
flood(x, y - 1, new_col, old_col);
}
}
int main()
{
int gd, gm = DETECT;
initgraph(&gd, &gm, "");
int top, left, bottom, right;
top = left = 50;
bottom = right = 300;
rectangle(left, top, right, bottom);
int x = 51;
int y = 51;
int newcolor = 12;
int oldcolor = 0;
flood(x, y, newcolor, oldcolor);
getch();
return 0;
}
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